A polyester fiber is a synthetic material. Polyester fibers are commonly used in the upholstered furniture industry as a filling component for seat and back cushions and/or as batting or padding of vertical and horizontal interior surfaces. Polyester fibers have replaced such previously used filling materials such as cotton and animal hair battings. Polyester is the dominant staple fiber used today for nonwoven flatgoods, highloft and densified synthetic textile applications.
Many companies currently produce synthetic filament and staple products. As an example, two companies and their common brand names for these synthetic fibers are DuPont DACRON.TM. (also, DuPont HOLLOFIL.TM.) and Hoechst Celanese TREVIRA.TM.. Other types of recognized staple fiber are polypropylene and rayon. As used herein, "staple" is fiber that is graded as to length and fineness (denier).
Polyester fibers are hair-like strands wherein the strands are generally solid fibers. However, with at least one type, HOLLOFIL.TM., hollow fibers are employed. When used for furniture seating applications, these fibers are processed into batting or filling using conventional methods such as garnetting or carding. In addition, synthetic fibers can also be "blown in" to a fabric casing, such as one used for a back cushion. "Bonding" is a conventional term of art, and, as used herein, describes a method of holding strands of fibers together in a practical and workable manner with the intention of creating a desired shape or form. Two examples of known types of bonding include resin bonding, which is characterized by its use of glues, and thermal bonding, which is characterized by its use of heat. Thermal bonding is preferred when drainage of liquid is an important consideration because resins impede the downward movement of liquids through the cushion, as will be discussed specifically below. In the textile product industry and as used herein, the term thermal bonding refers to a bonding technique which particularly utilizes a low-melt bicomponent binder.
A thermal bonded, densified fiber product can be manfactured into a variety of different textile products. Several such products relate to upholstered cushions or to cushion fillers, including the recently developed all-fiber seating filling components. Such a configuration can eliminate the use of a foam fill material. As previously stated, a thermal bonded all-fiber core or core/wrap combination encourages the downward movement of liquid through the textile product.
The self-draining properties of the all-fiber configurations provide a significant advantage over existing foams and resin-bonded fibers. The use of glues in these existing configurations blocks the flow of liquid. Flow-through movement of liquids (especially water) in cushion fillers as enabled by an all-fiber filler, is integral to the finished drainable cushion system (U.S. Pat. Nos. 4,914,772 and 5,005,241). Some common environments where the self-draining capabilities of all-fiber products are beneficial include upholstered indoor/outdoor furniture seating, marine seating, and sleep products.
Thermal bonded, high-loft, all-fiber filling products, however historically contain no supplemental components to reinforce the thermal bond sites. After repeated use or multiple compressions, the fibers can begin to collapse upon themselves. As the fibers collapse, the loft or resilience of the filling is reduced. Resilience is commonly used criteria to measure the quality of a filling or stuffing. As used herein, resilience is the ability to spring back or return to the original shape after being compressed or depressed by a form of pressure.
The textile industry has attempted a variety of different methods of treating fibers to create more resilience. An adage prevalent throughout the textile industry holds that the more fibers pet board foot, the more loft and resilience the product will exhibit. One particular method presently utilized to achieve more fiber content within a given area is a process referred to as thermal bonded densification, which is also often called "densified batting" or DB.
A variety of factors may affect exactly how much resilience or loft a particular filling displays. The contributing factors are whether the fibers are "dry" or siliconized (i.e. "wet"); and the density of the core/core wrap or core-only fiberfill. In addition, it is commonly recognized that there is a quantitative loss in the resilience of the filling or batting after repetitive use. Such a decline in resilience causes the cushion to lose both height and comfort.
Often times with traditional indoor cushions, polyurethane foam is used as a seat core or back fill. Even though foam is also subject to some fatigue or resilience loss after repetitive use, it may exhibit longer-lasting lofting properties than some all-fiber fillings. Futhermore, such foam seat cores may sometimes be supplemented with a type of internal support or springing (Ex: Marshall Units, Flexolator Grids). A mattress, for example, usually contains a type of innerspringing. As stated above, with regard to highloft fibers, however, a resilience or support type component is lacking as a supplement in thermal bonded fillers.
In addition, if a highloft fiber product 10 is made too dense, it becomes hard or does not exhibit a realistic degree of flexibility. Conversely, when made soft, the lack of fiber density allows for bonding site breakage, which reduces load bearing features and allows the fiber to move when compressed, therefore, causing a reduction of loft in the product. Currently, the synthetic fibers 18 utilized in all-fiber, thermal bonded fillers depend only on the matrix fiber 12 as combined with the bicomponent binder fiber 14 at a specified densification to achieve a desired cubic volume. There are no supplemental elements within the all-fiber thermal bonded fillers that serve as bond site fortifiers or reinforcers.
Currently, all-fiber batts 10, wraps, fillers, cores, etc. for high-loft applications may include a crimped polyester matrix fiber 12, a low-melt binder fiber 14 and utilize some type of fiber densifying process to interconnect the two types of fiber. The crimp 16 in the polyester matrix fiber 12 creates an "intermeshing" potential between the two fibers. Due to the presence of the low-melt binder fiber 14, a thermal bonding process may be used to bind the fibers 18 together during a machine densifying process. Such a thermal densification assists in creating more resilience, generally due to the presence of more fiber and fiber binder per given area as compared to a resin-type binder.
In order to achieve thermal bonding (the bonding of fibers 18 by a common heat source, and potentially microwaves), low-melt bicomponent or single component binder fibers, or binder powder, must be fused/joined with matrix fibers 12. The preferred binder, the bicomponent binder fiber 14, is commonly a sheath/core fiber (FIG. 6), with the core pan 20 generally being polyester. The binder 14 may be staple or continuous goods. Specifically, the surrounding sheath part 22 is often referred to as a "low-melting" polymer: When exposed to heat, the bicomponent fiber 14, with its melting characteristic, fuses or melts together with the surrounding matrix fibers 12. For seating/reclining components, as one example, the results can be a block or bait 10, etc., of desired dimension. Thermal bonding is also used for flatgood nonwovens, with different processes and applications involved. Two brands of bicomponent binder fiber are DuPont's Corebond.TM., and Hoecht Celanese's Celbond.TM..The present invention is directed at alleviating the above-stated shortcomings of the existing technology.